1. Field of the Invention
The invention relates to a horizontal-axis electrical machine having a laminated stator core which is braced in mutually spaced-apart support rings, that are arranged orthogonally with respect to the longitudinal machine axis. The rings are secured using mounting wedges distributed at the circumference of the machine, and are connected to the housing of the machine via mounting parts.
In this connection, the invention refers to a prior art as found, for example, in EP Patent Specification 0 166 114 or CH Patent Application 3557/88 of 23.09.1988 of the applicant.
2. Discussion of Background
In gas-cooled electrical machines of the entire power range, large axial and radial strains occur in the laminated stator core that must be transferred to the housing, distributed as uniformly as possible.
In the air-cooled turbine-driven generator known from EP Patent Specification 0 166 114, this is done by laterally suspending the laminated stator core with support plates which are arranged in parallel, and are perpendicular to the axis of the electrical machine, and are mutually spaced apart. In order to keep vibrations and thermal stresses which occur as small as possible during the operating state of the electrical machine, the support plates are annularly constructed and connected to the bottom part of the housing, by means of mounting parts, only two areas of their horizontal plane of symmetry on both sides, via extensions extending vertically in a straight line. By far the greatest proportion of the circumference of the support plates is spaced away from the bottom and top part of the housing. The laminated stator core is braced in the support plates, via mounting wedges uniformly distributed over its entire circumference. The mounting parts consist of mounting plates, which are in each case welded to the extensions of the support plates, and of horizontal-axis tubular pieces, which are welded to the mounting plates. This type of mounting of the laminated stator core allows simple assembly, easy accessibility of the constructional parts to be welded together, and ensures a good quality of the welds.
However, the known arrangement presupposes a housing which is approximately divided in the horizontal plane of symmetry of the machine in order to be able to insert the laminated stator core. Changing to hydrogen cooling is thus not easy because, in particular, the interfaces between bottom and top part of the housing are problematic with respect to sealing.
In order to be able to use an undivided housing in such machines, the CH Patent application initially mentioned proposes to have the mounting plates mounted at the annular support plates, and at different diameters which are stepped towards the other end as seen from one end of the machine, and correspondingly to step the associated mounting points at the housing. In this arrangement, the transverse walls are constructed of two parts and consist of a first ring which is mounted at the laminated stator core and a second ring which is mounted at the housing, the free ring ends overlapping, and a seal which is elastic in the axial direction being provided at the point of overlap. Seen from the other end of the machine, the outside diameters of the first rings are in each case smaller than the inside diameter of the second ring adjacent to it.
Such a design allows an undivided housing to be used because the laminated stator core (which may already be provided with the stator winding; a so-called built-in stator can be inserted into the housing. It is much simpler to make closed housings of this type gastight and they also withstand the higher gas pressures approximately 10 bar in the case of hydrogen cooling.
A disadvantage of both designs is that, due to the variety of welded connections, removal of the laminated core for repair and service purposes is difficult.